Reactant and catalyst structure/function relationships in the hydrocracking of alkyl-substituted biphenyl compounds

Catalytic hydrocracking is an extremely flexible process for the production of a wide range of upgraded products from heavy gas oils. The flexibility of the process originates from the use of a "tunable" bifunctional catalyst and high pressure hydrogen. The bifunctional catalyst required consists of a hydrogenation component and acidic cracking component.; The reactants in the feedstock can also be viewed as bifunctional, having aromatic and paraffinic functions. The overall observed reaction product spectrum is dependent upon the balancing of the acid and hydrogenation functions of the catalyst with the average properties of the reactant such as reactant's {dollar}prod{dollar}-electron density or heat of formation of a carbenium ion involved in the rate-determining step of the reaction sequence.; This dissertation has concentrated on studying the effects of the acid property of the catalyst on reaction pathways and kinetics of 9-ethyl fluorene, biphenyl, and 4-ethyl biphenyl. A formalism was developed to predict the rate constant for acid catalyzed reactions given: (1) an experimentally measured property of the catalyst and (2) calculated reactivity indices of the reactant involving the heats of formation of carbenium ions involved in the rate determining step, shown in equation 1.{dollar}{dollar}eqalign{lcub}log(ksb{lcub}obs{rcub})sb{lcub}ijl{rcub} &= asb{lcub}i{rcub} + bRIsb{lcub}ij{rcub} + csb{lcub}i{rcub}left({lcub}B/Lover B/L + 1{rcub}right)sb{lcub}sb l{rcub}cr i &=rm reaction familyqquadqquad (1)cr j &=rm reaction family membercr l &=rm catalyst{rcub}{dollar}{dollar}; The reaction model uses the rate constant of cumene dealkylation as a reactivity index for the acid function. Incorporated in the value of the cumene dealkylation rate constant is the combined effect of the number of acid sites and acid strength distributions of the materials. The cumene rate constant is then related to a measured property of the acid function.; The reactant portion of the reaction model is a set of linear free energy relationships for four main classes of reactions: disproportionation, isomerization, {dollar}beta{dollar}-scission cleavage, and hydrogenation. Thus, given the reactivity index of a reactant for a particular reaction, the rate constant for that reactant/reaction combination could be calculated using the ultimate model parameters of equation 1. Equation 1 provides a tool to predict conditions under which a particular reactant/reaction's selectivity is optimized relative to competing reactions.